Vehicle braking system with proportional poppet valve pressure control strategy

摘要

An electrohydraulic brake system where brake pressure is controlled by the combined action of an apply valve and a dump valve by the implementation of a method of controlling the voltage applied to the apply and dump valve. The EHB pressure control system receives a desired wheel pressure command and, with a caliper pressure feedback signal, implements an algorithm to compute one voltage command for the apply valve and another for the dump valve, corresponding to a requested flow from the hydraulics. The voltage command drives current control electronics. The electronics in turn power the solenoids of the proportional apply and dump poppet valves to control flow in or out of the brakes and modulate wheel pressure as required. Use of the algorithm to control the electromagnetic poppet valves achieves the commanded pressure at a vehicle's brakes reliably and with good control in all states of flow through the valve. The algorithm is a function of the existing pressure within the system and whether there is bulk or leakage flow through the valves.